JPH10308659A - Human body sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect a human body with a sensor of simple constitution liable to be less affected by erroneous detection owing to a metallic object or installation environment. SOLUTION: A high frequency signal of a single frequency is outputted from an oscillation part 12 and it is given to a sensor part 11 through a transmission line 14. The sensor part 11 is constituted of a detection coil 21, tow resonance capacitors 22a and 22b and a real number transformer 23. When a human body exists, the sensor part is set to resonate and a signal frequency of the oscillation part 12. A reflected wave level from the sensor part is low when the human body exists. When nothing exists and when other substance exists, the reflected wave level is high. The reflected wave level from the sensor part 11 is detected at a detection part 13 and an analog signal is amplified in a signal amplifier 53. A compactor 54 compares a magnitude of the signal with a reference value, and the presence or absence of the human body is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a human body sensor using a resonance circuit of a detection coil and a capacitor.

[0002]

2. Description of the Related Art The present inventors have developed a human body sensor including a resonance circuit including a detection coil and a capacitor. One of them is, as shown in FIG. 9, an oscillating unit 1 for oscillating a high-frequency signal, a detection circuit 2 for detecting a high-frequency signal output from the oscillating unit 1, and a detection signal from the detection circuit 2. And a control unit 3 for determining the presence or absence of a human body.

The oscillating unit 1 includes a detection coil 11a, a capacitor 12a connected in parallel to the detection coil 11a and having one end grounded, a resistor 13a connected in parallel to the capacitor 12a, An FET 14a having the other end connected to the gate, a series circuit of capacitors 15a and 16a connected between the gate of the FET 14a and the ground, and a resistor 1 connected in parallel with the capacitor 16a
7a. The connection point between the capacitors 15a and 16a is connected to the drain of the FET 14a.
The source of a is connected to the _Vcc power supply. This oscillator 1
Is a Colpitts-type LC oscillator, but other well-known oscillators, such as a Hartley oscillator, may also be used.

[0004] The detection unit 2 is an output terminal of the oscillation unit 1 FE
Capacitor 41 whose drain is connected to one end of T14a
And a cathode is connected to the other end of the capacitor 41,
A diode 42 whose anode is grounded; and a diode 43 whose anode is connected to the other end of the capacitor 41.
And a capacitor 44 connected between the cathode of the diode 43 and the ground. A detection signal is output from the cathode of the diode 43.

The control section 3 has an NPN transistor 31 to which the output signal of the detection section 2 is applied to the base, the emitter is grounded, and the collector outputs a signal indicating the presence or absence of a human body. When the oscillating unit 1 is oscillated in a state where the human body sensor 1 is incorporated in a seat, the output characteristics of the analog signal when the seat is vacant, when a child is seated, when an adult is seated, and when luggage is placed are A, b in FIG.
The characteristics shown in c and d are obtained. According to this, Q when the empty seats of a and b and the luggage are loaded is high and the analog output is low, and when the human body of b and c is seated, Q is small and the analog output is larger than a and d. . Therefore, if the ON / OFF reference value in the control unit 3 is set between the luggage and the child, the presence or absence of the seating of the human body can be detected.

As another human body sensor, there is a human body sensor shown in FIG. The human body sensor 10 includes a sensor unit 11, an oscillating unit 12 that transmits a high-frequency signal to the sensor unit 11 via a transmission path 14, and an oscillating unit that reflects the high-frequency signal supplied to the sensor unit 11 by the sensor 11. The apparatus comprises a reflected wave sensor section 13 for detecting a reflected signal returning to 12, and a control section 15 for taking in the detected reflected signal and performing signal processing. The sensor unit 11 includes a detection coil 21, a resonance capacitor 22 forming a series resonance circuit with the detection coil 21, a primary side connected to an input side resonance circuit, a secondary side connected to a high frequency input terminal 24 and a ground. GN
And a real number transformer 23 connected to D.

In the human body sensor 10, a high-frequency signal is generated by the oscillation unit 12 and supplied to the sensor unit 11 via the transmission line 14. The high frequency signal of the oscillating unit 12 is 30 MHz or more.
Scanning is performed in the range of 50 MHZ. The high-frequency signal supplied to the sensor unit 11 is reflected by the sensor unit 11. In the sensor unit 11, the impedance of the sensor unit 11 differs due to the difference in the magnetic permeability and the dielectric constant of the object depending on the object placed in the vicinity of the detection coil 21. Wave levels are different. This reflected wave is detected by the reflected wave sensor unit 13,
The control unit 15 discriminates and detects the vacant seat, baggage, human body, and the like based on the reflected wave level and frequency. That is, the oscillation unit 12
Oscillates, the characteristics of the reflected waves when the seat is vacant, when the child is seated, when the adult is seated, and when luggage is placed are the characteristics shown in a, b, c, and d of FIG. . According to this, when the vacant seats a and d and the luggage are placed, the reflected wave is very small and the Q is high at a certain frequency.
When the human bodies b and c are seated, the reflected wave becomes small at a certain frequency, but the degree of change is small and Q is small. Such a difference in the frequency characteristics of the reflected waves is caused by a difference in the magnetic permeability and the dielectric constant of the vacant seat (air), baggage, human body, and the like.

Therefore, if the level of the reflected wave detected by the reflected wave sensor unit 13 is larger than the reference value S _R set at the minimum point of the characteristic b and the characteristic d over the entire frequency range, the person is seated; Conversely, if there is a frequency of the reflected wave lower than the reference value S _R, it indicates that a vacant seat or luggage is placed, and the human body can be discriminated from the vacant seat or luggage.

[0009]

The above-mentioned conventional human body sensors are all susceptible to malfunctions caused by metal objects and the installation environment, and the former human body sensor does not have a coil detection range. Uniform and the latter human body sensor
Since a plurality of frequencies are used, there is a problem that a circuit system becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and is intended to provide a human body sensor which is not easily affected by a malfunction due to a metal object and an installation environment and which can detect a human body with a simple configuration and high accuracy. It is intended to provide.

[0011]

A human body sensor according to the present invention includes an oscillating section for outputting a single high-frequency signal, and a sensor section including a resonance circuit that receives a high-frequency signal from the oscillating section and resonates when the human body approaches. A detection unit that outputs an analog signal according to a change in impedance of the sensor unit; and a control unit that detects a human body from the output signal of the detection unit.

In this human body sensor, a high-frequency signal of a single frequency is output from the oscillating unit and is provided to the sensor unit.
In the state where no person is present in the vicinity of the sensor unit, matching on the input side cannot be performed due to its impedance, and a signal having a large reflected wave level is output from the detection unit. When a person is present, resonance occurs, impedance matching is achieved, and the level of the reflected wave is reduced. The presence or absence of a human body can be detected based on the level of the reflected wave.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to embodiments. FIG. 1 is a circuit diagram showing a circuit configuration of a human body sensor according to one embodiment of the present invention. In this embodiment, the human body sensor 10 includes a sensor section 11, an oscillating section 12 for generating a high-frequency signal, and a reflection of the high-frequency signal from the oscillating section 12 which is given to the sensor section 11 via a transmission line 14 and reflected. A detection unit 13 for detecting a wave and a control unit 15 for determining the presence or absence of a human body based on an analog signal from the detection unit 13 are provided, and in this regard, are similar to the human body sensor in FIG. However, this human body sensor 10
The oscillator 12 outputs a single-frequency high-frequency signal. This is different from the case where the human body sensor in FIG. 11 outputs high-frequency signals of a plurality of frequencies. The frequency of the high-frequency signal of the oscillating unit 12 is 10 MHz, but a frequency up to about 300 MHZ can be obtained with a simple circuit configuration and high sensitivity.

In the sensor section 11 of this embodiment, two ends of two resonance capacitors 22a and 22b are connected to both ends of a detection coil 21, and the other ends of the resonance capacitors 22a and 22b are connected to each other. Real number transformer 1
It is connected to both ends of the secondary coil and is a balanced circuit, which is also different from the human body sensor in FIG. Further, in the sensor section 11 and the oscillating section 12 of the human body sensor of this embodiment, the operating frequency and the resonance characteristics are set so as to be the characteristics shown in FIG. In other words, the level of the reflected wave is reduced by resonance because the setting is such that adult <child <vacant seat <luggage <metal, and the frequency at which the reflection level is minimal at the resonance point of the adult is used frequency f _s. It is set to be. Here, the reflected wave at the frequency f _s in the case where there is an adult and a child are set to be smaller than 50% to the incident wave. The detection coil 21 may be wound around a core or may be air-core. In the case of an air core, the core is not used, so the cost is low and it is easy to install under the seat.

[0015] In this embodiment the human body sensor 10, and outputs a high frequency signal of a frequency f _s from the oscillation unit 12. This high-frequency signal is sent to the sensor unit 11 via the transmission line 14 and is reflected. The reflected wave is detected by the detection unit 13, amplified by the signal amplifier 53, and compared with the reference value SR ₁ by the comparator 54. The analog signal from the detector 13 is the reference value S
Smaller than R ₁ determines that the human body Yes, it is determined that the human body without larger than the reference value SR _1. In this case, since there is little reduction in the reflection level of a metal in the used frequency f _s, is not to the human body there preparative false positives in the presence of a metal object. The same applies to non-metal luggage. Here, between the reflection level of the reflection level and child seated upon an adult is seated in the further operating frequency f _s in Fig. 2, further reference value SR
By setting ₂ , in addition to discriminating the presence or absence of a human body, it is possible to discriminate between adults and children.

FIG. 3 shows a human body sensor for detecting the distinction between an adult and a child. In this embodiment the human body sensor, two comparators 54a to the control unit 15, and 54b is provided, at the reference value SR ₁ and the reference value SR ₂ input voltage, and to compare, respectively. 1 and 3, the analog input signal amplified by the signal amplifier 53 is compared by the analog comparator 54 or the comparators 54a and 54b. As shown in FIG. 4, an A / D converter 55 for converting the output of the signal amplifier 53 from analog to digital, and a CPU 56 for fetching the input signal digitally and determining whether or not it is larger than the reference value SR ₁ or SR _2. May be provided.

Next, another embodiment of a human body sensor capable of detecting a seating position will be described. The circuit of the human body sensor in this embodiment is preferably the one shown in FIG. The detection coil 21 of the sensor unit 11 of the human body sensor is buried in a seat to be seated. When a person sits on this chair, the human body sensor naturally detects the presence of a human body. However, the level of the analog input signal at the time of sitting, as shown in FIG. 5, divides the seating position into three points: the front, the center, and the rear of the chair, and furthermore, the seating posture when sitting at each position. When the measurement is performed for the two types of leaning forward and normal posture, the levels are different from each other. Therefore, CPU5
In step 6, a reference value for separating these is set, compared with each reference value, and if the magnitude relation is checked, the seating position or the sitting posture can be detected.

FIG. 6 is a diagram showing a specific example of the detection coil of the sensor unit used in the human body sensor according to the embodiment. This human body sensor is used as a grip sensor, and the detection coil 21 is spirally wound around a cylindrical bobbin 26 and covered with an outer peripheral insulating material. The detection coil 21 may be connected to a circuit section inside the sensor main body 10 or a sensor section circuit may be provided in the bobbin 26 and connected to a resonance capacitor. As the entire circuit, for example, the circuit shown in FIG. 1 is used. In this grip sensor, when a person grips the grip of this sensor, this is detected by the detection coil 21 and the circuit unit is informed that the grip has been made.
Applications include motorbike handles.

FIG. 7 shows a grip sensor as a modification of FIG. 6, in which a spiral detection coil 21 is embedded in a handle 27 such as a pachinko machine. The operation is not particularly different from that of FIG. In the grip sensors of FIGS. 6 and 7, the analog signal (reflected wave) output from the detection unit when the user grips with bare hands and when gripping with gloves is as shown in FIG. In the case, the reflected wave level is larger, but there is no grip,
Since the level of the reflected wave at the operating frequency is lower than in the case where another substance or the like comes in contact, the detection can be sufficiently performed.

[0020]

According to the first aspect of the present invention, the high-frequency signal from the oscillating section to the sensor section has a single frequency, uses a reflected wave, and has the lowest reflected wave level in the presence of a human body. As a result, malfunctions caused by metal objects are eliminated. The circuit configuration that is less affected by the installation environment is simplified. Small size and low price can be realized. The detection range becomes uniform. And so on.

According to the second aspect of the invention, in addition to the effect of the first aspect, there is an effect that the common mode current is reduced. Further, according to the third aspect of the present invention, since the reflected wave when the human body is present is less than 50%, the human body can be reliably detected. Further, according to the invention according to claim 4, the oscillation frequency is 10 MHZ or more and 300 MHZ.
The following is an effect that high sensitivity can be obtained with a simple configuration. Further, according to the invention of claim 5, since one or more turns of the air-core coil are used as the detection coil, there is an effect that the cost is low and that the coil is easily installed under the seat. According to the invention according to claim 6, the human body can be reliably detected only by gripping the handle, and thereafter,
Necessary operations can be performed. Claim 7
According to the invention according to claim 8, not only the presence or absence of a human body but also the human body sitting position, the sitting posture, or the distinction between an adult and a child can be detected.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a human body sensor according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating reflected wave characteristics depending on the presence or absence of a human body in a sensor unit of the human body sensor according to the embodiment.

FIG. 3 is a circuit diagram showing a human body sensor according to another embodiment of the present invention.

FIG. 4 is a circuit diagram showing a human body sensor according to another embodiment of the present invention.

FIG. 5 is a diagram showing output voltages according to a sitting position and a sitting posture for explaining a human body sensor according to another embodiment of the present invention.

FIG. 6 is a diagram showing an example of a grip sensor which is a human body sensor according to another embodiment of the present invention.

FIG. 7 is a diagram showing another example of the grip sensor.

FIG. 8 is a diagram for explaining a difference in output voltage when using bare hands and gloves in the grip sensor.

FIG. 9 is a circuit diagram showing an example of a conventional human body sensor.

FIG. 10 is a diagram showing frequency-output voltage characteristics of the conventional human body sensor.

FIG. 11 is a circuit diagram showing another conventional human body sensor.

FIG. 12 is a diagram showing reflected wave characteristics of the conventional human body sensor of FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Sensor part 12 Oscillation part 13 Detection part 14 Transmission part 15 Control part 21 Detection coil 22a, 22b Resonant capacitor 23 Real number transformer 53 Signal amplifier 54 Comparator

Claims (8)

[Claims] An oscillator for outputting a single high-frequency signal, a sensor including a resonance circuit for receiving a high-frequency signal from the oscillator and resonating when approaching a human body, and responding to a change in impedance of the sensor. A detection unit that outputs an analog signal,
A control unit for detecting a human body from an output signal of the detection unit;
A human body sensor comprising: 2. The human body sensor according to claim 1, wherein the sensor section comprises a detection coil, two resonance capacitors, and a real transformer. 3. The human body sensor according to claim 1, wherein the sensor section has a small reflected wave when the human body is in the vicinity, and the reflected wave is less than 50% of the incident wave. 4. The human body sensor according to claim 1, wherein said oscillating section sets an oscillating frequency between 10 MHZ and 300 MHZ. 5. The sensing coil of the sensor section is an air-core coil having one or more turns.
A human body sensor as described. 6. The human body sensor according to claim 2, wherein the detection coil of the sensor unit is incorporated in a human body contact part. 7. The control unit according to claim 1, wherein the control unit detects a seating position or a sitting posture of a human body in accordance with an analog signal of the detecting unit. The human body sensor according to claim 5 or 6. 8. The control unit according to claim 1, wherein the control unit detects presence / absence of a human body and the distinction between an adult and a child according to an analog signal of the detection unit. The human body sensor according to claim 5 or claim 6.